A scope having a zoom mechanism that includes a cam tube holding an optical train of lenses whose relative positions change when said cam tube is rotated, causing an image seen through the scope to expand or contract. A gear is in contact to said cam tube and is positioned so as to rotate said cam tube when said gear is rotated. Finally, an actuator is positioned on a side of said scope and operatively connected to said gear so that said actuator causes said gear to turn when a user moves said actuator.